Individual authentication methods can be classified into 3 kinds of authentications, i.e., authentication by knowledge, authentication by belongings, and authentication by biological information. The authentication by knowledge includes, for example, authentication by a password and the authentication by belongings includes, for example, authentication by a magnetic card with a magnetic stripe or an IC card with an IC chip. Also, the authentication by biological information includes authentication by a fingerprint, authentication by a vein, and authentication by an iris.
Also, in the authentication by belongings, there is a method in which a key apparatus including key information performs communication with another external apparatus for authentication. For example, PTL 1 discloses a technology for sharing a common personal identification number between an external apparatus and a key apparatus and performing unlocking or locking using the shared personal identification number.